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Unverified Commit a34e011e by Niels Lohmann Committed by GitHub
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Merge pull request #2576 from AnthonyVH/non_default_constructable_stl_containers

Add support for deserialization of STL containers of non-default constructable types (fixes #2574).
parents f1600cd2 2b865131
Showing with 782 additions and 376 deletions
include/nlohmann/adl_serializer.hpp
#pragma once
#include <type_traits>
#include <utility>
#include <nlohmann/detail/conversions/from_json.hpp>
#include <nlohmann/detail/conversions/to_json.hpp>
#include <nlohmann/detail/meta/identity_tag.hpp>
#include <nlohmann/detail/meta/type_traits.hpp>
namespace nlohmann
{
template<typename, typename>
template<typename ValueType, typename>
struct adl_serializer
{
/*!
......@@ -17,11 +20,13 @@ struct adl_serializer
This function is usually called by the `get()` function of the
@ref basic_json class (either explicit or via conversion operators).
@note This function is chosen for default-constructible value types.
@param[in] j JSON value to read from
@param[in,out] val value to write to
*/
template<typename BasicJsonType, typename ValueType>
static auto from_json(BasicJsonType&& j, ValueType& val) noexcept(
template<typename BasicJsonType, typename TargetType = ValueType>
static auto from_json(BasicJsonType && j, TargetType& val) noexcept(
noexcept(::nlohmann::from_json(std::forward<BasicJsonType>(j), val)))
-> decltype(::nlohmann::from_json(std::forward<BasicJsonType>(j), val), void())
{
......@@ -29,6 +34,26 @@ struct adl_serializer
}
/*!
@brief convert a JSON value to any value type
This function is usually called by the `get()` function of the
@ref basic_json class (either explicit or via conversion operators).
@note This function is chosen for value types which are not default-constructible.
@param[in] j JSON value to read from
@return copy of the JSON value, converted to @a ValueType
*/
template<typename BasicJsonType, typename TargetType = ValueType>
static auto from_json(BasicJsonType && j) noexcept(
noexcept(::nlohmann::from_json(std::forward<BasicJsonType>(j), detail::identity_tag<TargetType> {})))
-> decltype(::nlohmann::from_json(std::forward<BasicJsonType>(j), detail::identity_tag<TargetType> {}))
{
return ::nlohmann::from_json(std::forward<BasicJsonType>(j), detail::identity_tag<TargetType> {});
}
/*!
@brief convert any value type to a JSON value
This function is usually called by the constructors of the @ref basic_json
......@@ -37,13 +62,12 @@ struct adl_serializer
@param[in,out] j JSON value to write to
@param[in] val value to read from
*/
template<typename BasicJsonType, typename ValueType>
static auto to_json(BasicJsonType& j, ValueType&& val) noexcept(
noexcept(::nlohmann::to_json(j, std::forward<ValueType>(val))))
-> decltype(::nlohmann::to_json(j, std::forward<ValueType>(val)), void())
template<typename BasicJsonType, typename TargetType = ValueType>
static auto to_json(BasicJsonType& j, TargetType && val) noexcept(
noexcept(::nlohmann::to_json(j, std::forward<TargetType>(val))))
-> decltype(::nlohmann::to_json(j, std::forward<TargetType>(val)), void())
{
::nlohmann::to_json(j, std::forward<ValueType>(val));
::nlohmann::to_json(j, std::forward<TargetType>(val));
}
};
} // namespace nlohmann
include/nlohmann/detail/conversions/from_json.hpp
......@@ -15,6 +15,7 @@
#include <nlohmann/detail/exceptions.hpp>
#include <nlohmann/detail/macro_scope.hpp>
#include <nlohmann/detail/meta/cpp_future.hpp>
#include <nlohmann/detail/meta/identity_tag.hpp>
#include <nlohmann/detail/meta/type_traits.hpp>
#include <nlohmann/detail/value_t.hpp>
......@@ -187,7 +188,10 @@ auto from_json_array_impl(const BasicJsonType& j, std::array<T, N>& arr,
}
}
template<typename BasicJsonType, typename ConstructibleArrayType>
template<typename BasicJsonType, typename ConstructibleArrayType,
enable_if_t<
std::is_assignable<ConstructibleArrayType&, ConstructibleArrayType>::value,
int> = 0>
auto from_json_array_impl(const BasicJsonType& j, ConstructibleArrayType& arr, priority_tag<1> /*unused*/)
-> decltype(
arr.reserve(std::declval<typename ConstructibleArrayType::size_type>()),
......@@ -208,7 +212,10 @@ auto from_json_array_impl(const BasicJsonType& j, ConstructibleArrayType& arr, p
arr = std::move(ret);
}
template<typename BasicJsonType, typename ConstructibleArrayType>
template<typename BasicJsonType, typename ConstructibleArrayType,
enable_if_t<
std::is_assignable<ConstructibleArrayType&, ConstructibleArrayType>::value,
int> = 0>
void from_json_array_impl(const BasicJsonType& j, ConstructibleArrayType& arr,
priority_tag<0> /*unused*/)
{
......@@ -247,6 +254,25 @@ void())
from_json_array_impl(j, arr, priority_tag<3> {});
}
template < typename BasicJsonType, typename T, std::size_t... Idx >
std::array<T, sizeof...(Idx)> from_json_inplace_array_impl(BasicJsonType&& j,
identity_tag<std::array<T, sizeof...(Idx)>> /*unused*/, index_sequence<Idx...> /*unused*/)
{
return { { std::forward<BasicJsonType>(j).at(Idx).template get<T>()... } };
}
template < typename BasicJsonType, typename T, std::size_t N >
auto from_json(BasicJsonType&& j, identity_tag<std::array<T, N>> tag)
-> decltype(from_json_inplace_array_impl(std::forward<BasicJsonType>(j), tag, make_index_sequence<N> {}))
{
if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
{
JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name()), j));
}
return from_json_inplace_array_impl(std::forward<BasicJsonType>(j), tag, make_index_sequence<N> {});
}
template<typename BasicJsonType>
void from_json(const BasicJsonType& j, typename BasicJsonType::binary_t& bin)
{
......@@ -322,22 +348,47 @@ void from_json(const BasicJsonType& j, ArithmeticType& val)
}
}
template<typename BasicJsonType, typename... Args, std::size_t... Idx>
std::tuple<Args...> from_json_tuple_impl_base(BasicJsonType&& j, index_sequence<Idx...> /*unused*/)
{
return std::make_tuple(std::forward<BasicJsonType>(j).at(Idx).template get<Args>()...);
}
template < typename BasicJsonType, class A1, class A2 >
std::pair<A1, A2> from_json_tuple_impl(BasicJsonType&& j, identity_tag<std::pair<A1, A2>> /*unused*/, priority_tag<0> /*unused*/)
{
return {std::forward<BasicJsonType>(j).at(0).template get<A1>(),
std::forward<BasicJsonType>(j).at(1).template get<A2>()};
}
template<typename BasicJsonType, typename A1, typename A2>
void from_json(const BasicJsonType& j, std::pair<A1, A2>& p)
void from_json_tuple_impl(BasicJsonType&& j, std::pair<A1, A2>& p, priority_tag<1> /*unused*/)
{
p = {j.at(0).template get<A1>(), j.at(1).template get<A2>()};
p = from_json_tuple_impl(std::forward<BasicJsonType>(j), identity_tag<std::pair<A1, A2>> {}, priority_tag<0> {});
}
template<typename BasicJsonType, typename Tuple, std::size_t... Idx>
void from_json_tuple_impl(const BasicJsonType& j, Tuple& t, index_sequence<Idx...> /*unused*/)
template<typename BasicJsonType, typename... Args>
std::tuple<Args...> from_json_tuple_impl(BasicJsonType&& j, identity_tag<std::tuple<Args...>> /*unused*/, priority_tag<2> /*unused*/)
{
t = std::make_tuple(j.at(Idx).template get<typename std::tuple_element<Idx, Tuple>::type>()...);
return from_json_tuple_impl_base<BasicJsonType, Args...>(std::forward<BasicJsonType>(j), index_sequence_for<Args...> {});
}
template<typename BasicJsonType, typename... Args>
void from_json(const BasicJsonType& j, std::tuple<Args...>& t)
void from_json_tuple_impl(BasicJsonType&& j, std::tuple<Args...>& t, priority_tag<3> /*unused*/)
{
from_json_tuple_impl(j, t, index_sequence_for<Args...> {});
t = from_json_tuple_impl_base<BasicJsonType, Args...>(std::forward<BasicJsonType>(j), index_sequence_for<Args...> {});
}
template<typename BasicJsonType, typename TupleRelated>
auto from_json(BasicJsonType&& j, TupleRelated&& t)
-> decltype(from_json_tuple_impl(std::forward<BasicJsonType>(j), std::forward<TupleRelated>(t), priority_tag<3> {}))
{
if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
{
JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name()), j));
}
return from_json_tuple_impl(std::forward<BasicJsonType>(j), std::forward<TupleRelated>(t), priority_tag<3> {});
}
template < typename BasicJsonType, typename Key, typename Value, typename Compare, typename Allocator,
......@@ -383,11 +434,11 @@ void from_json(const BasicJsonType& j, std::unordered_map<Key, Value, Hash, KeyE
struct from_json_fn
{
template<typename BasicJsonType, typename T>
auto operator()(const BasicJsonType& j, T& val) const
noexcept(noexcept(from_json(j, val)))
-> decltype(from_json(j, val), void())
auto operator()(const BasicJsonType& j, T&& val) const
noexcept(noexcept(from_json(j, std::forward<T>(val))))
-> decltype(from_json(j, std::forward<T>(val)))
{
return from_json(j, val);
return from_json(j, std::forward<T>(val));
}
};
} // namespace detail
......
include/nlohmann/detail/meta/identity_tag.hpp 0 → 100644
#pragma once
namespace nlohmann
{
namespace detail
{
// dispatching helper struct
template <class T> struct identity_tag {};
} // namespace detail
} // namespace nlohmann
include/nlohmann/detail/meta/type_traits.hpp
......@@ -106,8 +106,7 @@ struct is_getable
};
template<typename BasicJsonType, typename T>
struct has_from_json < BasicJsonType, T,
enable_if_t < !is_basic_json<T>::value >>
struct has_from_json < BasicJsonType, T, enable_if_t < !is_basic_json<T>::value >>
{
using serializer = typename BasicJsonType::template json_serializer<T, void>;
......@@ -151,6 +150,52 @@ struct has_to_json < BasicJsonType, T, enable_if_t < !is_basic_json<T>::value >>
// is_ functions //
///////////////////
// https://en.cppreference.com/w/cpp/types/conjunction
template<class...> struct conjunction : std::true_type { };
template<class B1> struct conjunction<B1> : B1 { };
template<class B1, class... Bn>
struct conjunction<B1, Bn...>
: std::conditional<bool(B1::value), conjunction<Bn...>, B1>::type {};
// Reimplementation of is_constructible and is_default_constructible, due to them being broken for
// std::pair and std::tuple until LWG 2367 fix (see https://cplusplus.github.io/LWG/lwg-defects.html#2367).
// This causes compile errors in e.g. clang 3.5 or gcc 4.9.
template <typename T>
struct is_default_constructible : std::is_default_constructible<T> {};
template <typename T1, typename T2>
struct is_default_constructible<std::pair<T1, T2>>
: conjunction<is_default_constructible<T1>, is_default_constructible<T2>> {};
template <typename T1, typename T2>
struct is_default_constructible<const std::pair<T1, T2>>
: conjunction<is_default_constructible<T1>, is_default_constructible<T2>> {};
template <typename... Ts>
struct is_default_constructible<std::tuple<Ts...>>
: conjunction<is_default_constructible<Ts>...> {};
template <typename... Ts>
struct is_default_constructible<const std::tuple<Ts...>>
: conjunction<is_default_constructible<Ts>...> {};
template <typename T, typename... Args>
struct is_constructible : std::is_constructible<T, Args...> {};
template <typename T1, typename T2>
struct is_constructible<std::pair<T1, T2>> : is_default_constructible<std::pair<T1, T2>> {};
template <typename T1, typename T2>
struct is_constructible<const std::pair<T1, T2>> : is_default_constructible<const std::pair<T1, T2>> {};
template <typename... Ts>
struct is_constructible<std::tuple<Ts...>> : is_default_constructible<std::tuple<Ts...>> {};
template <typename... Ts>
struct is_constructible<const std::tuple<Ts...>> : is_default_constructible<const std::tuple<Ts...>> {};
template<typename T, typename = void>
struct is_iterator_traits : std::false_type {};
......@@ -193,9 +238,9 @@ struct is_compatible_object_type_impl <
// macOS's is_constructible does not play well with nonesuch...
static constexpr bool value =
std::is_constructible<typename object_t::key_type,
is_constructible<typename object_t::key_type,
typename CompatibleObjectType::key_type>::value &&
std::is_constructible<typename object_t::mapped_type,
is_constructible<typename object_t::mapped_type,
typename CompatibleObjectType::mapped_type>::value;
};
......@@ -216,10 +261,10 @@ struct is_constructible_object_type_impl <
using object_t = typename BasicJsonType::object_t;
static constexpr bool value =
(std::is_default_constructible<ConstructibleObjectType>::value &&
(is_default_constructible<ConstructibleObjectType>::value &&
(std::is_move_assignable<ConstructibleObjectType>::value ||
std::is_copy_assignable<ConstructibleObjectType>::value) &&
(std::is_constructible<typename ConstructibleObjectType::key_type,
(is_constructible<typename ConstructibleObjectType::key_type,
typename object_t::key_type>::value &&
std::is_same <
typename object_t::mapped_type,
......@@ -247,7 +292,7 @@ struct is_compatible_string_type_impl <
value_type_t, CompatibleStringType>::value >>
{
static constexpr auto value =
std::is_constructible<typename BasicJsonType::string_t, CompatibleStringType>::value;
is_constructible<typename BasicJsonType::string_t, CompatibleStringType>::value;
};
template<typename BasicJsonType, typename ConstructibleStringType>
......@@ -265,7 +310,7 @@ struct is_constructible_string_type_impl <
value_type_t, ConstructibleStringType>::value >>
{
static constexpr auto value =
std::is_constructible<ConstructibleStringType,
is_constructible<ConstructibleStringType,
typename BasicJsonType::string_t>::value;
};
......@@ -288,7 +333,7 @@ struct is_compatible_array_type_impl <
iterator_traits<CompatibleArrayType >>::value >>
{
static constexpr bool value =
std::is_constructible<BasicJsonType,
is_constructible<BasicJsonType,
typename CompatibleArrayType::value_type>::value;
};
......@@ -311,7 +356,7 @@ struct is_constructible_array_type_impl <
BasicJsonType, ConstructibleArrayType,
enable_if_t < !std::is_same<ConstructibleArrayType,
typename BasicJsonType::value_type>::value&&
std::is_default_constructible<ConstructibleArrayType>::value&&
is_default_constructible<ConstructibleArrayType>::value&&
(std::is_move_assignable<ConstructibleArrayType>::value ||
std::is_copy_assignable<ConstructibleArrayType>::value)&&
is_detected<value_type_t, ConstructibleArrayType>::value&&
......@@ -355,7 +400,7 @@ struct is_compatible_integer_type_impl <
using CompatibleLimits = std::numeric_limits<CompatibleNumberIntegerType>;
static constexpr auto value =
std::is_constructible<RealIntegerType,
is_constructible<RealIntegerType,
CompatibleNumberIntegerType>::value &&
CompatibleLimits::is_integer &&
RealLimits::is_signed == CompatibleLimits::is_signed;
......@@ -382,17 +427,10 @@ template<typename BasicJsonType, typename CompatibleType>
struct is_compatible_type
: is_compatible_type_impl<BasicJsonType, CompatibleType> {};
// https://en.cppreference.com/w/cpp/types/conjunction
template<class...> struct conjunction : std::true_type { };
template<class B1> struct conjunction<B1> : B1 { };
template<class B1, class... Bn>
struct conjunction<B1, Bn...>
: std::conditional<bool(B1::value), conjunction<Bn...>, B1>::type {};
template<typename T1, typename T2>
struct is_constructible_tuple : std::false_type {};
template<typename T1, typename... Args>
struct is_constructible_tuple<T1, std::tuple<Args...>> : conjunction<std::is_constructible<T1, Args>...> {};
struct is_constructible_tuple<T1, std::tuple<Args...>> : conjunction<is_constructible<T1, Args>...> {};
} // namespace detail
} // namespace nlohmann
include/nlohmann/json.hpp
......@@ -2920,50 +2920,53 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
/// @{
/*!
@brief get special-case overload
@brief get a pointer value (implicit)
This overloads avoids a lot of template boilerplate, it can be seen as the
identity method
Implicit pointer access to the internally stored JSON value. No copies are
made.
@tparam BasicJsonType == @ref basic_json
@warning Writing data to the pointee of the result yields an undefined
state.
@return a copy of *this
@tparam PointerType pointer type; must be a pointer to @ref array_t, @ref
object_t, @ref string_t, @ref boolean_t, @ref number_integer_t,
@ref number_unsigned_t, or @ref number_float_t. Enforced by a static
assertion.
@return pointer to the internally stored JSON value if the requested
pointer type @a PointerType fits to the JSON value; `nullptr` otherwise
@complexity Constant.
@since version 2.1.0
@liveexample{The example below shows how pointers to internal values of a
JSON value can be requested. Note that no type conversions are made and a
`nullptr` is returned if the value and the requested pointer type does not
match.,get_ptr}
@since version 1.0.0
*/
template<typename BasicJsonType, detail::enable_if_t<
std::is_same<typename std::remove_const<BasicJsonType>::type, basic_json_t>::value,
int> = 0>
basic_json get() const
template<typename PointerType, typename std::enable_if<
std::is_pointer<PointerType>::value, int>::type = 0>
auto get_ptr() noexcept -> decltype(std::declval<basic_json_t&>().get_impl_ptr(std::declval<PointerType>()))
{
return *this;
// delegate the call to get_impl_ptr<>()
return get_impl_ptr(static_cast<PointerType>(nullptr));
}
/*!
@brief get special-case overload
This overloads converts the current @ref basic_json in a different
@ref basic_json type
@tparam BasicJsonType == @ref basic_json
@return a copy of *this, converted into @a BasicJsonType
@complexity Depending on the implementation of the called `from_json()`
method.
@since version 3.2.0
@brief get a pointer value (implicit)
@copydoc get_ptr()
*/
template < typename BasicJsonType, detail::enable_if_t <
!std::is_same<BasicJsonType, basic_json>::value&&
detail::is_basic_json<BasicJsonType>::value, int > = 0 >
BasicJsonType get() const
template < typename PointerType, typename std::enable_if <
std::is_pointer<PointerType>::value&&
std::is_const<typename std::remove_pointer<PointerType>::type>::value, int >::type = 0 >
constexpr auto get_ptr() const noexcept -> decltype(std::declval<const basic_json_t&>().get_impl_ptr(std::declval<PointerType>()))
{
return *this;
// delegate the call to get_impl_ptr<>() const
return get_impl_ptr(static_cast<PointerType>(nullptr));
}
private:
/*!
@brief get a value (explicit)
......@@ -2987,7 +2990,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
- @ref json_serializer<ValueType> does not have a `from_json()` method of
the form `ValueType from_json(const basic_json&)`
@tparam ValueTypeCV the provided value type
@tparam ValueType the returned value type
@return copy of the JSON value, converted to @a ValueType
......@@ -3003,23 +3005,14 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@since version 2.1.0
*/
template < typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>,
template < typename ValueType,
detail::enable_if_t <
!detail::is_basic_json<ValueType>::value &&
detail::has_from_json<basic_json_t, ValueType>::value &&
!detail::has_non_default_from_json<basic_json_t, ValueType>::value,
detail::is_default_constructible<ValueType>::value&&
detail::has_from_json<basic_json_t, ValueType>::value,
int > = 0 >
ValueType get() const noexcept(noexcept(
JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), std::declval<ValueType&>())))
ValueType get_impl(detail::priority_tag<0> /*unused*/) const noexcept(noexcept(
JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), std::declval<ValueType&>())))
{
// we cannot static_assert on ValueTypeCV being non-const, because
// there is support for get<const basic_json_t>(), which is why we
// still need the uncvref
static_assert(!std::is_reference<ValueTypeCV>::value,
"get() cannot be used with reference types, you might want to use get_ref()");
static_assert(std::is_default_constructible<ValueType>::value,
"types must be DefaultConstructible when used with get()");
ValueType ret{};
JSONSerializer<ValueType>::from_json(*this, ret);
return ret;
......@@ -3036,7 +3029,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
The function is equivalent to executing
@code {.cpp}
return JSONSerializer<ValueTypeCV>::from_json(*this);
return JSONSerializer<ValueType>::from_json(*this);
@endcode
This overloads is chosen if:
......@@ -3047,7 +3040,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@note If @ref json_serializer<ValueType> has both overloads of
`from_json()`, this one is chosen.
@tparam ValueTypeCV the provided value type
@tparam ValueType the returned value type
@return copy of the JSON value, converted to @a ValueType
......@@ -3056,134 +3048,116 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@since version 2.1.0
*/
template < typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>,
detail::enable_if_t < !std::is_same<basic_json_t, ValueType>::value &&
detail::has_non_default_from_json<basic_json_t, ValueType>::value,
int > = 0 >
ValueType get() const noexcept(noexcept(
JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>())))
template < typename ValueType,
detail::enable_if_t <
detail::has_non_default_from_json<basic_json_t, ValueType>::value,
int > = 0 >
ValueType get_impl(detail::priority_tag<1> /*unused*/) const noexcept(noexcept(
JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>())))
{
static_assert(!std::is_reference<ValueTypeCV>::value,
"get() cannot be used with reference types, you might want to use get_ref()");
return JSONSerializer<ValueType>::from_json(*this);
}
/*!
@brief get a value (explicit)
Explicit type conversion between the JSON value and a compatible value.
The value is filled into the input parameter by calling the @ref json_serializer<ValueType>
`from_json()` method.
The function is equivalent to executing
@code {.cpp}
ValueType v;
JSONSerializer<ValueType>::from_json(*this, v);
@endcode
This overloads is chosen if:
- @a ValueType is not @ref basic_json,
- @ref json_serializer<ValueType> has a `from_json()` method of the form
`void from_json(const basic_json&, ValueType&)`, and
@brief get special-case overload
@tparam ValueType the input parameter type.
This overloads converts the current @ref basic_json in a different
@ref basic_json type
@return the input parameter, allowing chaining calls.
@tparam BasicJsonType == @ref basic_json
@throw what @ref json_serializer<ValueType> `from_json()` method throws
@return a copy of *this, converted into @a BasicJsonType
@liveexample{The example below shows several conversions from JSON values
to other types. There a few things to note: (1) Floating-point numbers can
be converted to integers\, (2) A JSON array can be converted to a standard
`std::vector<short>`\, (3) A JSON object can be converted to C++
associative containers such as `std::unordered_map<std::string\,
json>`.,get_to}
@complexity Depending on the implementation of the called `from_json()`
method.
@since version 3.3.0
@since version 3.2.0
*/
template < typename ValueType,
template < typename BasicJsonType,
detail::enable_if_t <
!detail::is_basic_json<ValueType>::value&&
detail::has_from_json<basic_json_t, ValueType>::value,
detail::is_basic_json<BasicJsonType>::value,
int > = 0 >
ValueType & get_to(ValueType& v) const noexcept(noexcept(
JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), v)))
BasicJsonType get_impl(detail::priority_tag<2> /*unused*/) const
{
JSONSerializer<ValueType>::from_json(*this, v);
return v;
return *this;
}
// specialization to allow to call get_to with a basic_json value
// see https://github.com/nlohmann/json/issues/2175
template<typename ValueType,
detail::enable_if_t <
detail::is_basic_json<ValueType>::value,
/*!
@brief get special-case overload
This overloads avoids a lot of template boilerplate, it can be seen as the
identity method
@tparam BasicJsonType == @ref basic_json
@return a copy of *this
@complexity Constant.
@since version 2.1.0
*/
template<typename BasicJsonType,
detail::enable_if_t<
std::is_same<BasicJsonType, basic_json_t>::value,
int> = 0>
ValueType & get_to(ValueType& v) const
basic_json get_impl(detail::priority_tag<3> /*unused*/) const
{
v = *this;
return v;
return *this;
}
template <
typename T, std::size_t N,
typename Array = T (&)[N], // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
detail::enable_if_t <
detail::has_from_json<basic_json_t, Array>::value, int > = 0 >
Array get_to(T (&v)[N]) const // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
noexcept(noexcept(JSONSerializer<Array>::from_json(
std::declval<const basic_json_t&>(), v)))
/*!
@brief get a pointer value (explicit)
@copydoc get()
*/
template<typename PointerType,
detail::enable_if_t<
std::is_pointer<PointerType>::value,
int> = 0>
constexpr auto get_impl(detail::priority_tag<4> /*unused*/) const noexcept
-> decltype(std::declval<const basic_json_t&>().template get_ptr<PointerType>())
{
JSONSerializer<Array>::from_json(*this, v);
return v;
// delegate the call to get_ptr
return get_ptr<PointerType>();
}
public:
/*!
@brief get a pointer value (implicit)
@brief get a (pointer) value (explicit)
Implicit pointer access to the internally stored JSON value. No copies are
made.
Performs explicit type conversion between the JSON value and a compatible value if required.
@warning Writing data to the pointee of the result yields an undefined
state.
- If the requested type is a pointer to the internally stored JSON value that pointer is returned.
No copies are made.
@tparam PointerType pointer type; must be a pointer to @ref array_t, @ref
object_t, @ref string_t, @ref boolean_t, @ref number_integer_t,
@ref number_unsigned_t, or @ref number_float_t. Enforced by a static
assertion.
- If the requested type is the current @ref basic_json, or a different @ref basic_json convertible
from the current @ref basic_json.
@return pointer to the internally stored JSON value if the requested
pointer type @a PointerType fits to the JSON value; `nullptr` otherwise
- Otherwise the value is converted by calling the @ref json_serializer<ValueType> `from_json()`
method.
@complexity Constant.
@tparam ValueTypeCV the provided value type
@tparam ValueType the returned value type
@liveexample{The example below shows how pointers to internal values of a
JSON value can be requested. Note that no type conversions are made and a
`nullptr` is returned if the value and the requested pointer type does not
match.,get_ptr}
@return copy of the JSON value, converted to @tparam ValueType if necessary
@since version 1.0.0
*/
template<typename PointerType, typename std::enable_if<
std::is_pointer<PointerType>::value, int>::type = 0>
auto get_ptr() noexcept -> decltype(std::declval<basic_json_t&>().get_impl_ptr(std::declval<PointerType>()))
{
// delegate the call to get_impl_ptr<>()
return get_impl_ptr(static_cast<PointerType>(nullptr));
}
@throw what @ref json_serializer<ValueType> `from_json()` method throws if conversion is required
/*!
@brief get a pointer value (implicit)
@copydoc get_ptr()
@since version 2.1.0
*/
template < typename PointerType, typename std::enable_if <
std::is_pointer<PointerType>::value&&
std::is_const<typename std::remove_pointer<PointerType>::type>::value, int >::type = 0 >
constexpr auto get_ptr() const noexcept -> decltype(std::declval<const basic_json_t&>().get_impl_ptr(std::declval<PointerType>()))
template < typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>>
#if defined(JSON_HAS_CPP_14)
constexpr
#endif
auto get() const noexcept(
noexcept(std::declval<const basic_json_t&>().template get_impl<ValueType>(detail::priority_tag<4> {})))
-> decltype(std::declval<const basic_json_t&>().template get_impl<ValueType>(detail::priority_tag<4> {}))
{
// delegate the call to get_impl_ptr<>() const
return get_impl_ptr(static_cast<PointerType>(nullptr));
// we cannot static_assert on ValueTypeCV being non-const, because
// there is support for get<const basic_json_t>(), which is why we
// still need the uncvref
static_assert(!std::is_reference<ValueTypeCV>::value,
"get() cannot be used with reference types, you might want to use get_ref()");
return get_impl<ValueType>(detail::priority_tag<4> {});
}
/*!
......@@ -3222,15 +3196,73 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
}
/*!
@brief get a pointer value (explicit)
@copydoc get()
@brief get a value (explicit)
Explicit type conversion between the JSON value and a compatible value.
The value is filled into the input parameter by calling the @ref json_serializer<ValueType>
`from_json()` method.
The function is equivalent to executing
@code {.cpp}
ValueType v;
JSONSerializer<ValueType>::from_json(*this, v);
@endcode
This overloads is chosen if:
- @a ValueType is not @ref basic_json,
- @ref json_serializer<ValueType> has a `from_json()` method of the form
`void from_json(const basic_json&, ValueType&)`, and
@tparam ValueType the input parameter type.
@return the input parameter, allowing chaining calls.
@throw what @ref json_serializer<ValueType> `from_json()` method throws
@liveexample{The example below shows several conversions from JSON values
to other types. There a few things to note: (1) Floating-point numbers can
be converted to integers\, (2) A JSON array can be converted to a standard
`std::vector<short>`\, (3) A JSON object can be converted to C++
associative containers such as `std::unordered_map<std::string\,
json>`.,get_to}
@since version 3.3.0
*/
template<typename PointerType, typename std::enable_if<
std::is_pointer<PointerType>::value, int>::type = 0>
constexpr auto get() const noexcept -> decltype(std::declval<const basic_json_t&>().template get_ptr<PointerType>())
template < typename ValueType,
detail::enable_if_t <
!detail::is_basic_json<ValueType>::value&&
detail::has_from_json<basic_json_t, ValueType>::value,
int > = 0 >
ValueType & get_to(ValueType& v) const noexcept(noexcept(
JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), v)))
{
// delegate the call to get_ptr
return get_ptr<PointerType>();
JSONSerializer<ValueType>::from_json(*this, v);
return v;
}
// specialization to allow to call get_to with a basic_json value
// see https://github.com/nlohmann/json/issues/2175
template<typename ValueType,
detail::enable_if_t <
detail::is_basic_json<ValueType>::value,
int> = 0>
ValueType & get_to(ValueType& v) const
{
v = *this;
return v;
}
template <
typename T, std::size_t N,
typename Array = T (&)[N], // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
detail::enable_if_t <
detail::has_from_json<basic_json_t, Array>::value, int > = 0 >
Array get_to(T (&v)[N]) const // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
noexcept(noexcept(JSONSerializer<Array>::from_json(
std::declval<const basic_json_t&>(), v)))
{
JSONSerializer<Array>::from_json(*this, v);
return v;
}
/*!
......
single_include/nlohmann/json.hpp
......@@ -49,6 +49,7 @@ SOFTWARE.
// #include <nlohmann/adl_serializer.hpp>
#include <type_traits>
#include <utility>
// #include <nlohmann/detail/conversions/from_json.hpp>
......@@ -3166,6 +3167,18 @@ constexpr T static_const<T>::value;
} // namespace detail
} // namespace nlohmann
// #include <nlohmann/detail/meta/identity_tag.hpp>
namespace nlohmann
{
namespace detail
{
// dispatching helper struct
template <class T> struct identity_tag {};
} // namespace detail
} // namespace nlohmann
// #include <nlohmann/detail/meta/type_traits.hpp>
......@@ -3483,8 +3496,7 @@ struct is_getable
};
template<typename BasicJsonType, typename T>
struct has_from_json < BasicJsonType, T,
enable_if_t < !is_basic_json<T>::value >>
struct has_from_json < BasicJsonType, T, enable_if_t < !is_basic_json<T>::value >>
{
using serializer = typename BasicJsonType::template json_serializer<T, void>;
......@@ -3528,6 +3540,52 @@ struct has_to_json < BasicJsonType, T, enable_if_t < !is_basic_json<T>::value >>
// is_ functions //
///////////////////
// https://en.cppreference.com/w/cpp/types/conjunction
template<class...> struct conjunction : std::true_type { };
template<class B1> struct conjunction<B1> : B1 { };
template<class B1, class... Bn>
struct conjunction<B1, Bn...>
: std::conditional<bool(B1::value), conjunction<Bn...>, B1>::type {};
// Reimplementation of is_constructible and is_default_constructible, due to them being broken for
// std::pair and std::tuple until LWG 2367 fix (see https://cplusplus.github.io/LWG/lwg-defects.html#2367).
// This causes compile errors in e.g. clang 3.5 or gcc 4.9.
template <typename T>
struct is_default_constructible : std::is_default_constructible<T> {};
template <typename T1, typename T2>
struct is_default_constructible<std::pair<T1, T2>>
: conjunction<is_default_constructible<T1>, is_default_constructible<T2>> {};
template <typename T1, typename T2>
struct is_default_constructible<const std::pair<T1, T2>>
: conjunction<is_default_constructible<T1>, is_default_constructible<T2>> {};
template <typename... Ts>
struct is_default_constructible<std::tuple<Ts...>>
: conjunction<is_default_constructible<Ts>...> {};
template <typename... Ts>
struct is_default_constructible<const std::tuple<Ts...>>
: conjunction<is_default_constructible<Ts>...> {};
template <typename T, typename... Args>
struct is_constructible : std::is_constructible<T, Args...> {};
template <typename T1, typename T2>
struct is_constructible<std::pair<T1, T2>> : is_default_constructible<std::pair<T1, T2>> {};
template <typename T1, typename T2>
struct is_constructible<const std::pair<T1, T2>> : is_default_constructible<const std::pair<T1, T2>> {};
template <typename... Ts>
struct is_constructible<std::tuple<Ts...>> : is_default_constructible<std::tuple<Ts...>> {};
template <typename... Ts>
struct is_constructible<const std::tuple<Ts...>> : is_default_constructible<const std::tuple<Ts...>> {};
template<typename T, typename = void>
struct is_iterator_traits : std::false_type {};
......@@ -3570,9 +3628,9 @@ struct is_compatible_object_type_impl <
// macOS's is_constructible does not play well with nonesuch...
static constexpr bool value =
std::is_constructible<typename object_t::key_type,
is_constructible<typename object_t::key_type,
typename CompatibleObjectType::key_type>::value &&
std::is_constructible<typename object_t::mapped_type,
is_constructible<typename object_t::mapped_type,
typename CompatibleObjectType::mapped_type>::value;
};
......@@ -3593,10 +3651,10 @@ struct is_constructible_object_type_impl <
using object_t = typename BasicJsonType::object_t;
static constexpr bool value =
(std::is_default_constructible<ConstructibleObjectType>::value &&
(is_default_constructible<ConstructibleObjectType>::value &&
(std::is_move_assignable<ConstructibleObjectType>::value ||
std::is_copy_assignable<ConstructibleObjectType>::value) &&
(std::is_constructible<typename ConstructibleObjectType::key_type,
(is_constructible<typename ConstructibleObjectType::key_type,
typename object_t::key_type>::value &&
std::is_same <
typename object_t::mapped_type,
......@@ -3624,7 +3682,7 @@ struct is_compatible_string_type_impl <
value_type_t, CompatibleStringType>::value >>
{
static constexpr auto value =
std::is_constructible<typename BasicJsonType::string_t, CompatibleStringType>::value;
is_constructible<typename BasicJsonType::string_t, CompatibleStringType>::value;
};
template<typename BasicJsonType, typename ConstructibleStringType>
......@@ -3642,7 +3700,7 @@ struct is_constructible_string_type_impl <
value_type_t, ConstructibleStringType>::value >>
{
static constexpr auto value =
std::is_constructible<ConstructibleStringType,
is_constructible<ConstructibleStringType,
typename BasicJsonType::string_t>::value;
};
......@@ -3665,7 +3723,7 @@ struct is_compatible_array_type_impl <
iterator_traits<CompatibleArrayType >>::value >>
{
static constexpr bool value =
std::is_constructible<BasicJsonType,
is_constructible<BasicJsonType,
typename CompatibleArrayType::value_type>::value;
};
......@@ -3688,7 +3746,7 @@ struct is_constructible_array_type_impl <
BasicJsonType, ConstructibleArrayType,
enable_if_t < !std::is_same<ConstructibleArrayType,
typename BasicJsonType::value_type>::value&&
std::is_default_constructible<ConstructibleArrayType>::value&&
is_default_constructible<ConstructibleArrayType>::value&&
(std::is_move_assignable<ConstructibleArrayType>::value ||
std::is_copy_assignable<ConstructibleArrayType>::value)&&
is_detected<value_type_t, ConstructibleArrayType>::value&&
......@@ -3732,7 +3790,7 @@ struct is_compatible_integer_type_impl <
using CompatibleLimits = std::numeric_limits<CompatibleNumberIntegerType>;
static constexpr auto value =
std::is_constructible<RealIntegerType,
is_constructible<RealIntegerType,
CompatibleNumberIntegerType>::value &&
CompatibleLimits::is_integer &&
RealLimits::is_signed == CompatibleLimits::is_signed;
......@@ -3759,18 +3817,11 @@ template<typename BasicJsonType, typename CompatibleType>
struct is_compatible_type
: is_compatible_type_impl<BasicJsonType, CompatibleType> {};
// https://en.cppreference.com/w/cpp/types/conjunction
template<class...> struct conjunction : std::true_type { };
template<class B1> struct conjunction<B1> : B1 { };
template<class B1, class... Bn>
struct conjunction<B1, Bn...>
: std::conditional<bool(B1::value), conjunction<Bn...>, B1>::type {};
template<typename T1, typename T2>
struct is_constructible_tuple : std::false_type {};
template<typename T1, typename... Args>
struct is_constructible_tuple<T1, std::tuple<Args...>> : conjunction<std::is_constructible<T1, Args>...> {};
struct is_constructible_tuple<T1, std::tuple<Args...>> : conjunction<is_constructible<T1, Args>...> {};
} // namespace detail
} // namespace nlohmann
......@@ -3946,7 +3997,10 @@ auto from_json_array_impl(const BasicJsonType& j, std::array<T, N>& arr,
}
}
template<typename BasicJsonType, typename ConstructibleArrayType>
template<typename BasicJsonType, typename ConstructibleArrayType,
enable_if_t<
std::is_assignable<ConstructibleArrayType&, ConstructibleArrayType>::value,
int> = 0>
auto from_json_array_impl(const BasicJsonType& j, ConstructibleArrayType& arr, priority_tag<1> /*unused*/)
-> decltype(
arr.reserve(std::declval<typename ConstructibleArrayType::size_type>()),
......@@ -3967,7 +4021,10 @@ auto from_json_array_impl(const BasicJsonType& j, ConstructibleArrayType& arr, p
arr = std::move(ret);
}
template<typename BasicJsonType, typename ConstructibleArrayType>
template<typename BasicJsonType, typename ConstructibleArrayType,
enable_if_t<
std::is_assignable<ConstructibleArrayType&, ConstructibleArrayType>::value,
int> = 0>
void from_json_array_impl(const BasicJsonType& j, ConstructibleArrayType& arr,
priority_tag<0> /*unused*/)
{
......@@ -4006,6 +4063,25 @@ void())
from_json_array_impl(j, arr, priority_tag<3> {});
}
template < typename BasicJsonType, typename T, std::size_t... Idx >
std::array<T, sizeof...(Idx)> from_json_inplace_array_impl(BasicJsonType&& j,
identity_tag<std::array<T, sizeof...(Idx)>> /*unused*/, index_sequence<Idx...> /*unused*/)
{
return { { std::forward<BasicJsonType>(j).at(Idx).template get<T>()... } };
}
template < typename BasicJsonType, typename T, std::size_t N >
auto from_json(BasicJsonType&& j, identity_tag<std::array<T, N>> tag)
-> decltype(from_json_inplace_array_impl(std::forward<BasicJsonType>(j), tag, make_index_sequence<N> {}))
{
if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
{
JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name()), j));
}
return from_json_inplace_array_impl(std::forward<BasicJsonType>(j), tag, make_index_sequence<N> {});
}
template<typename BasicJsonType>
void from_json(const BasicJsonType& j, typename BasicJsonType::binary_t& bin)
{
......@@ -4081,22 +4157,47 @@ void from_json(const BasicJsonType& j, ArithmeticType& val)
}
}
template<typename BasicJsonType, typename... Args, std::size_t... Idx>
std::tuple<Args...> from_json_tuple_impl_base(BasicJsonType&& j, index_sequence<Idx...> /*unused*/)
{
return std::make_tuple(std::forward<BasicJsonType>(j).at(Idx).template get<Args>()...);
}
template < typename BasicJsonType, class A1, class A2 >
std::pair<A1, A2> from_json_tuple_impl(BasicJsonType&& j, identity_tag<std::pair<A1, A2>> /*unused*/, priority_tag<0> /*unused*/)
{
return {std::forward<BasicJsonType>(j).at(0).template get<A1>(),
std::forward<BasicJsonType>(j).at(1).template get<A2>()};
}
template<typename BasicJsonType, typename A1, typename A2>
void from_json(const BasicJsonType& j, std::pair<A1, A2>& p)
void from_json_tuple_impl(BasicJsonType&& j, std::pair<A1, A2>& p, priority_tag<1> /*unused*/)
{
p = {j.at(0).template get<A1>(), j.at(1).template get<A2>()};
p = from_json_tuple_impl(std::forward<BasicJsonType>(j), identity_tag<std::pair<A1, A2>> {}, priority_tag<0> {});
}
template<typename BasicJsonType, typename Tuple, std::size_t... Idx>
void from_json_tuple_impl(const BasicJsonType& j, Tuple& t, index_sequence<Idx...> /*unused*/)
template<typename BasicJsonType, typename... Args>
std::tuple<Args...> from_json_tuple_impl(BasicJsonType&& j, identity_tag<std::tuple<Args...>> /*unused*/, priority_tag<2> /*unused*/)
{
t = std::make_tuple(j.at(Idx).template get<typename std::tuple_element<Idx, Tuple>::type>()...);
return from_json_tuple_impl_base<BasicJsonType, Args...>(std::forward<BasicJsonType>(j), index_sequence_for<Args...> {});
}
template<typename BasicJsonType, typename... Args>
void from_json(const BasicJsonType& j, std::tuple<Args...>& t)
void from_json_tuple_impl(BasicJsonType&& j, std::tuple<Args...>& t, priority_tag<3> /*unused*/)
{
from_json_tuple_impl(j, t, index_sequence_for<Args...> {});
t = from_json_tuple_impl_base<BasicJsonType, Args...>(std::forward<BasicJsonType>(j), index_sequence_for<Args...> {});
}
template<typename BasicJsonType, typename TupleRelated>
auto from_json(BasicJsonType&& j, TupleRelated&& t)
-> decltype(from_json_tuple_impl(std::forward<BasicJsonType>(j), std::forward<TupleRelated>(t), priority_tag<3> {}))
{
if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
{
JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name()), j));
}
return from_json_tuple_impl(std::forward<BasicJsonType>(j), std::forward<TupleRelated>(t), priority_tag<3> {});
}
template < typename BasicJsonType, typename Key, typename Value, typename Compare, typename Allocator,
......@@ -4142,11 +4243,11 @@ void from_json(const BasicJsonType& j, std::unordered_map<Key, Value, Hash, KeyE
struct from_json_fn
{
template<typename BasicJsonType, typename T>
auto operator()(const BasicJsonType& j, T& val) const
noexcept(noexcept(from_json(j, val)))
-> decltype(from_json(j, val), void())
auto operator()(const BasicJsonType& j, T&& val) const
noexcept(noexcept(from_json(j, std::forward<T>(val))))
-> decltype(from_json(j, std::forward<T>(val)))
{
return from_json(j, val);
return from_json(j, std::forward<T>(val));
}
};
} // namespace detail
......@@ -4731,11 +4832,15 @@ constexpr const auto& to_json = detail::static_const<detail::to_json_fn>::value;
} // namespace
} // namespace nlohmann
// #include <nlohmann/detail/meta/identity_tag.hpp>
// #include <nlohmann/detail/meta/type_traits.hpp>
namespace nlohmann
{
template<typename, typename>
template<typename ValueType, typename>
struct adl_serializer
{
/*!
......@@ -4744,11 +4849,13 @@ struct adl_serializer
This function is usually called by the `get()` function of the
@ref basic_json class (either explicit or via conversion operators).
@note This function is chosen for default-constructible value types.
@param[in] j JSON value to read from
@param[in,out] val value to write to
*/
template<typename BasicJsonType, typename ValueType>
static auto from_json(BasicJsonType&& j, ValueType& val) noexcept(
template<typename BasicJsonType, typename TargetType = ValueType>
static auto from_json(BasicJsonType && j, TargetType& val) noexcept(
noexcept(::nlohmann::from_json(std::forward<BasicJsonType>(j), val)))
-> decltype(::nlohmann::from_json(std::forward<BasicJsonType>(j), val), void())
{
......@@ -4756,6 +4863,26 @@ struct adl_serializer
}
/*!
@brief convert a JSON value to any value type
This function is usually called by the `get()` function of the
@ref basic_json class (either explicit or via conversion operators).
@note This function is chosen for value types which are not default-constructible.
@param[in] j JSON value to read from
@return copy of the JSON value, converted to @a ValueType
*/
template<typename BasicJsonType, typename TargetType = ValueType>
static auto from_json(BasicJsonType && j) noexcept(
noexcept(::nlohmann::from_json(std::forward<BasicJsonType>(j), detail::identity_tag<TargetType> {})))
-> decltype(::nlohmann::from_json(std::forward<BasicJsonType>(j), detail::identity_tag<TargetType> {}))
{
return ::nlohmann::from_json(std::forward<BasicJsonType>(j), detail::identity_tag<TargetType> {});
}
/*!
@brief convert any value type to a JSON value
This function is usually called by the constructors of the @ref basic_json
......@@ -4764,15 +4891,14 @@ struct adl_serializer
@param[in,out] j JSON value to write to
@param[in] val value to read from
*/
template<typename BasicJsonType, typename ValueType>
static auto to_json(BasicJsonType& j, ValueType&& val) noexcept(
noexcept(::nlohmann::to_json(j, std::forward<ValueType>(val))))
-> decltype(::nlohmann::to_json(j, std::forward<ValueType>(val)), void())
template<typename BasicJsonType, typename TargetType = ValueType>
static auto to_json(BasicJsonType& j, TargetType && val) noexcept(
noexcept(::nlohmann::to_json(j, std::forward<TargetType>(val))))
-> decltype(::nlohmann::to_json(j, std::forward<TargetType>(val)), void())
{
::nlohmann::to_json(j, std::forward<ValueType>(val));
::nlohmann::to_json(j, std::forward<TargetType>(val));
}
};
} // namespace nlohmann
// #include <nlohmann/byte_container_with_subtype.hpp>
......@@ -19809,50 +19935,53 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
/// @{
/*!
@brief get special-case overload
@brief get a pointer value (implicit)
This overloads avoids a lot of template boilerplate, it can be seen as the
identity method
Implicit pointer access to the internally stored JSON value. No copies are
made.
@tparam BasicJsonType == @ref basic_json
@warning Writing data to the pointee of the result yields an undefined
state.
@return a copy of *this
@tparam PointerType pointer type; must be a pointer to @ref array_t, @ref
object_t, @ref string_t, @ref boolean_t, @ref number_integer_t,
@ref number_unsigned_t, or @ref number_float_t. Enforced by a static
assertion.
@return pointer to the internally stored JSON value if the requested
pointer type @a PointerType fits to the JSON value; `nullptr` otherwise
@complexity Constant.
@since version 2.1.0
@liveexample{The example below shows how pointers to internal values of a
JSON value can be requested. Note that no type conversions are made and a
`nullptr` is returned if the value and the requested pointer type does not
match.,get_ptr}
@since version 1.0.0
*/
template<typename BasicJsonType, detail::enable_if_t<
std::is_same<typename std::remove_const<BasicJsonType>::type, basic_json_t>::value,
int> = 0>
basic_json get() const
template<typename PointerType, typename std::enable_if<
std::is_pointer<PointerType>::value, int>::type = 0>
auto get_ptr() noexcept -> decltype(std::declval<basic_json_t&>().get_impl_ptr(std::declval<PointerType>()))
{
return *this;
// delegate the call to get_impl_ptr<>()
return get_impl_ptr(static_cast<PointerType>(nullptr));
}
/*!
@brief get special-case overload
This overloads converts the current @ref basic_json in a different
@ref basic_json type
@tparam BasicJsonType == @ref basic_json
@return a copy of *this, converted into @a BasicJsonType
@complexity Depending on the implementation of the called `from_json()`
method.
@since version 3.2.0
@brief get a pointer value (implicit)
@copydoc get_ptr()
*/
template < typename BasicJsonType, detail::enable_if_t <
!std::is_same<BasicJsonType, basic_json>::value&&
detail::is_basic_json<BasicJsonType>::value, int > = 0 >
BasicJsonType get() const
template < typename PointerType, typename std::enable_if <
std::is_pointer<PointerType>::value&&
std::is_const<typename std::remove_pointer<PointerType>::type>::value, int >::type = 0 >
constexpr auto get_ptr() const noexcept -> decltype(std::declval<const basic_json_t&>().get_impl_ptr(std::declval<PointerType>()))
{
return *this;
// delegate the call to get_impl_ptr<>() const
return get_impl_ptr(static_cast<PointerType>(nullptr));
}
private:
/*!
@brief get a value (explicit)
......@@ -19876,7 +20005,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
- @ref json_serializer<ValueType> does not have a `from_json()` method of
the form `ValueType from_json(const basic_json&)`
@tparam ValueTypeCV the provided value type
@tparam ValueType the returned value type
@return copy of the JSON value, converted to @a ValueType
......@@ -19892,23 +20020,14 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@since version 2.1.0
*/
template < typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>,
template < typename ValueType,
detail::enable_if_t <
!detail::is_basic_json<ValueType>::value &&
detail::has_from_json<basic_json_t, ValueType>::value &&
!detail::has_non_default_from_json<basic_json_t, ValueType>::value,
detail::is_default_constructible<ValueType>::value&&
detail::has_from_json<basic_json_t, ValueType>::value,
int > = 0 >
ValueType get() const noexcept(noexcept(
JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), std::declval<ValueType&>())))
ValueType get_impl(detail::priority_tag<0> /*unused*/) const noexcept(noexcept(
JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), std::declval<ValueType&>())))
{
// we cannot static_assert on ValueTypeCV being non-const, because
// there is support for get<const basic_json_t>(), which is why we
// still need the uncvref
static_assert(!std::is_reference<ValueTypeCV>::value,
"get() cannot be used with reference types, you might want to use get_ref()");
static_assert(std::is_default_constructible<ValueType>::value,
"types must be DefaultConstructible when used with get()");
ValueType ret{};
JSONSerializer<ValueType>::from_json(*this, ret);
return ret;
......@@ -19925,7 +20044,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
The function is equivalent to executing
@code {.cpp}
return JSONSerializer<ValueTypeCV>::from_json(*this);
return JSONSerializer<ValueType>::from_json(*this);
@endcode
This overloads is chosen if:
......@@ -19936,7 +20055,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@note If @ref json_serializer<ValueType> has both overloads of
`from_json()`, this one is chosen.
@tparam ValueTypeCV the provided value type
@tparam ValueType the returned value type
@return copy of the JSON value, converted to @a ValueType
......@@ -19945,134 +20063,116 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@since version 2.1.0
*/
template < typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>,
detail::enable_if_t < !std::is_same<basic_json_t, ValueType>::value &&
detail::has_non_default_from_json<basic_json_t, ValueType>::value,
int > = 0 >
ValueType get() const noexcept(noexcept(
JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>())))
template < typename ValueType,
detail::enable_if_t <
detail::has_non_default_from_json<basic_json_t, ValueType>::value,
int > = 0 >
ValueType get_impl(detail::priority_tag<1> /*unused*/) const noexcept(noexcept(
JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>())))
{
static_assert(!std::is_reference<ValueTypeCV>::value,
"get() cannot be used with reference types, you might want to use get_ref()");
return JSONSerializer<ValueType>::from_json(*this);
}
/*!
@brief get a value (explicit)
Explicit type conversion between the JSON value and a compatible value.
The value is filled into the input parameter by calling the @ref json_serializer<ValueType>
`from_json()` method.
The function is equivalent to executing
@code {.cpp}
ValueType v;
JSONSerializer<ValueType>::from_json(*this, v);
@endcode
This overloads is chosen if:
- @a ValueType is not @ref basic_json,
- @ref json_serializer<ValueType> has a `from_json()` method of the form
`void from_json(const basic_json&, ValueType&)`, and
@brief get special-case overload
@tparam ValueType the input parameter type.
This overloads converts the current @ref basic_json in a different
@ref basic_json type
@return the input parameter, allowing chaining calls.
@tparam BasicJsonType == @ref basic_json
@throw what @ref json_serializer<ValueType> `from_json()` method throws
@return a copy of *this, converted into @a BasicJsonType
@liveexample{The example below shows several conversions from JSON values
to other types. There a few things to note: (1) Floating-point numbers can
be converted to integers\, (2) A JSON array can be converted to a standard
`std::vector<short>`\, (3) A JSON object can be converted to C++
associative containers such as `std::unordered_map<std::string\,
json>`.,get_to}
@complexity Depending on the implementation of the called `from_json()`
method.
@since version 3.3.0
@since version 3.2.0
*/
template < typename ValueType,
template < typename BasicJsonType,
detail::enable_if_t <
!detail::is_basic_json<ValueType>::value&&
detail::has_from_json<basic_json_t, ValueType>::value,
detail::is_basic_json<BasicJsonType>::value,
int > = 0 >
ValueType & get_to(ValueType& v) const noexcept(noexcept(
JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), v)))
BasicJsonType get_impl(detail::priority_tag<2> /*unused*/) const
{
JSONSerializer<ValueType>::from_json(*this, v);
return v;
return *this;
}
// specialization to allow to call get_to with a basic_json value
// see https://github.com/nlohmann/json/issues/2175
template<typename ValueType,
detail::enable_if_t <
detail::is_basic_json<ValueType>::value,
/*!
@brief get special-case overload
This overloads avoids a lot of template boilerplate, it can be seen as the
identity method
@tparam BasicJsonType == @ref basic_json
@return a copy of *this
@complexity Constant.
@since version 2.1.0
*/
template<typename BasicJsonType,
detail::enable_if_t<
std::is_same<BasicJsonType, basic_json_t>::value,
int> = 0>
ValueType & get_to(ValueType& v) const
basic_json get_impl(detail::priority_tag<3> /*unused*/) const
{
v = *this;
return v;
return *this;
}
template <
typename T, std::size_t N,
typename Array = T (&)[N], // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
detail::enable_if_t <
detail::has_from_json<basic_json_t, Array>::value, int > = 0 >
Array get_to(T (&v)[N]) const // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
noexcept(noexcept(JSONSerializer<Array>::from_json(
std::declval<const basic_json_t&>(), v)))
/*!
@brief get a pointer value (explicit)
@copydoc get()
*/
template<typename PointerType,
detail::enable_if_t<
std::is_pointer<PointerType>::value,
int> = 0>
constexpr auto get_impl(detail::priority_tag<4> /*unused*/) const noexcept
-> decltype(std::declval<const basic_json_t&>().template get_ptr<PointerType>())
{
JSONSerializer<Array>::from_json(*this, v);
return v;
// delegate the call to get_ptr
return get_ptr<PointerType>();
}
public:
/*!
@brief get a pointer value (implicit)
@brief get a (pointer) value (explicit)
Implicit pointer access to the internally stored JSON value. No copies are
made.
Performs explicit type conversion between the JSON value and a compatible value if required.
@warning Writing data to the pointee of the result yields an undefined
state.
- If the requested type is a pointer to the internally stored JSON value that pointer is returned.
No copies are made.
@tparam PointerType pointer type; must be a pointer to @ref array_t, @ref
object_t, @ref string_t, @ref boolean_t, @ref number_integer_t,
@ref number_unsigned_t, or @ref number_float_t. Enforced by a static
assertion.
- If the requested type is the current @ref basic_json, or a different @ref basic_json convertible
from the current @ref basic_json.
@return pointer to the internally stored JSON value if the requested
pointer type @a PointerType fits to the JSON value; `nullptr` otherwise
- Otherwise the value is converted by calling the @ref json_serializer<ValueType> `from_json()`
method.
@complexity Constant.
@tparam ValueTypeCV the provided value type
@tparam ValueType the returned value type
@liveexample{The example below shows how pointers to internal values of a
JSON value can be requested. Note that no type conversions are made and a
`nullptr` is returned if the value and the requested pointer type does not
match.,get_ptr}
@return copy of the JSON value, converted to @tparam ValueType if necessary
@since version 1.0.0
*/
template<typename PointerType, typename std::enable_if<
std::is_pointer<PointerType>::value, int>::type = 0>
auto get_ptr() noexcept -> decltype(std::declval<basic_json_t&>().get_impl_ptr(std::declval<PointerType>()))
{
// delegate the call to get_impl_ptr<>()
return get_impl_ptr(static_cast<PointerType>(nullptr));
}
@throw what @ref json_serializer<ValueType> `from_json()` method throws if conversion is required
/*!
@brief get a pointer value (implicit)
@copydoc get_ptr()
@since version 2.1.0
*/
template < typename PointerType, typename std::enable_if <
std::is_pointer<PointerType>::value&&
std::is_const<typename std::remove_pointer<PointerType>::type>::value, int >::type = 0 >
constexpr auto get_ptr() const noexcept -> decltype(std::declval<const basic_json_t&>().get_impl_ptr(std::declval<PointerType>()))
template < typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>>
#if defined(JSON_HAS_CPP_14)
constexpr
#endif
auto get() const noexcept(
noexcept(std::declval<const basic_json_t&>().template get_impl<ValueType>(detail::priority_tag<4> {})))
-> decltype(std::declval<const basic_json_t&>().template get_impl<ValueType>(detail::priority_tag<4> {}))
{
// delegate the call to get_impl_ptr<>() const
return get_impl_ptr(static_cast<PointerType>(nullptr));
// we cannot static_assert on ValueTypeCV being non-const, because
// there is support for get<const basic_json_t>(), which is why we
// still need the uncvref
static_assert(!std::is_reference<ValueTypeCV>::value,
"get() cannot be used with reference types, you might want to use get_ref()");
return get_impl<ValueType>(detail::priority_tag<4> {});
}
/*!
......@@ -20111,15 +20211,73 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
}
/*!
@brief get a pointer value (explicit)
@copydoc get()
@brief get a value (explicit)
Explicit type conversion between the JSON value and a compatible value.
The value is filled into the input parameter by calling the @ref json_serializer<ValueType>
`from_json()` method.
The function is equivalent to executing
@code {.cpp}
ValueType v;
JSONSerializer<ValueType>::from_json(*this, v);
@endcode
This overloads is chosen if:
- @a ValueType is not @ref basic_json,
- @ref json_serializer<ValueType> has a `from_json()` method of the form
`void from_json(const basic_json&, ValueType&)`, and
@tparam ValueType the input parameter type.
@return the input parameter, allowing chaining calls.
@throw what @ref json_serializer<ValueType> `from_json()` method throws
@liveexample{The example below shows several conversions from JSON values
to other types. There a few things to note: (1) Floating-point numbers can
be converted to integers\, (2) A JSON array can be converted to a standard
`std::vector<short>`\, (3) A JSON object can be converted to C++
associative containers such as `std::unordered_map<std::string\,
json>`.,get_to}
@since version 3.3.0
*/
template<typename PointerType, typename std::enable_if<
std::is_pointer<PointerType>::value, int>::type = 0>
constexpr auto get() const noexcept -> decltype(std::declval<const basic_json_t&>().template get_ptr<PointerType>())
template < typename ValueType,
detail::enable_if_t <
!detail::is_basic_json<ValueType>::value&&
detail::has_from_json<basic_json_t, ValueType>::value,
int > = 0 >
ValueType & get_to(ValueType& v) const noexcept(noexcept(
JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), v)))
{
// delegate the call to get_ptr
return get_ptr<PointerType>();
JSONSerializer<ValueType>::from_json(*this, v);
return v;
}
// specialization to allow to call get_to with a basic_json value
// see https://github.com/nlohmann/json/issues/2175
template<typename ValueType,
detail::enable_if_t <
detail::is_basic_json<ValueType>::value,
int> = 0>
ValueType & get_to(ValueType& v) const
{
v = *this;
return v;
}
template <
typename T, std::size_t N,
typename Array = T (&)[N], // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
detail::enable_if_t <
detail::has_from_json<basic_json_t, Array>::value, int > = 0 >
Array get_to(T (&v)[N]) const // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
noexcept(noexcept(JSONSerializer<Array>::from_json(
std::declval<const basic_json_t&>(), v)))
{
JSONSerializer<Array>::from_json(*this, v);
return v;
}
/*!
......
test/src/unit-regression2.cpp
......@@ -134,6 +134,29 @@ struct NotSerializableData
};
/////////////////////////////////////////////////////////////////////
// for #2574
/////////////////////////////////////////////////////////////////////
struct NonDefaultConstructible
{
explicit NonDefaultConstructible (int a) : x(a) { }
int x;
};
namespace nlohmann
{
template <>
struct adl_serializer<NonDefaultConstructible>
{
static NonDefaultConstructible from_json (json const& j)
{
return NonDefaultConstructible(j.get<int>());
}
};
} // namespace nlohmann
TEST_CASE("regression tests 2")
{
SECTION("issue #1001 - Fix memory leak during parser callback")
......@@ -501,4 +524,74 @@ TEST_CASE("regression tests 2")
CHECK(j.dump() == "\"Hello, world!\"");
}
#endif
SECTION("issue #2574 - Deserialization to std::array, std::pair, and std::tuple with non-default constructable types fails")
{
SECTION("std::array")
{
{
json j = { 7, 4 };
auto arr = j.get<std::array<NonDefaultConstructible, 2>>();
CHECK(arr[0].x == 7);
CHECK(arr[1].x == 4);
}
{
json j = 7;
CHECK_THROWS_AS((j.get<std::array<NonDefaultConstructible, 1>>()), json::type_error);
}
}
SECTION("std::pair")
{
{
json j = { 3, 8 };
auto p = j.get<std::pair<NonDefaultConstructible, NonDefaultConstructible>>();
CHECK(p.first.x == 3);
CHECK(p.second.x == 8);
}
{
json j = { 4, 1 };
auto p = j.get<std::pair<int, NonDefaultConstructible>>();
CHECK(p.first == 4);
CHECK(p.second.x == 1);
}
{
json j = { 6, 7 };
auto p = j.get<std::pair<NonDefaultConstructible, int>>();
CHECK(p.first.x == 6);
CHECK(p.second == 7);
}
{
json j = 7;
CHECK_THROWS_AS((j.get<std::pair<NonDefaultConstructible, int>>()), json::type_error);
}
}
SECTION("std::tuple")
{
{
json j = { 9 };
auto t = j.get<std::tuple<NonDefaultConstructible>>();
CHECK(std::get<0>(t).x == 9);
}
{
json j = { 9, 8, 7 };
auto t = j.get<std::tuple<NonDefaultConstructible, int, NonDefaultConstructible>>();
CHECK(std::get<0>(t).x == 9);
CHECK(std::get<1>(t) == 8);
CHECK(std::get<2>(t).x == 7);
}
{
json j = 7;
CHECK_THROWS_AS((j.get<std::tuple<NonDefaultConstructible>>()), json::type_error);
}
}
}
}
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